A method of diagnosis and treatment of tumors using High Intensity Focused Ultrasound is provided. The method of diagnosing the presence of a tumor in a patient comprises the steps of subjecting a tumor to high intensity focused ultrasound (HIFU) to cause the tumor cells to release cellular material and evaluating the cellular material for a tumor marker. The method of treating a tumor in a patient can also comprise the step of subjecting a tumor to high intensity focused ultrasound (HIFU) to provoke an immune response.